Ball point pen



Jan. 31, 1961 F, SCH'ACHTER 2,969,583

BALL POINT PEN Filed Sept. 8, 1958 I 2 Sheets-Sheet 1 INVENTOR.Fla/5021ca /1mm? Jan. 31, 1961 sc c 2,969,583

BALL POINT PEN Filed Sept. 8, 1958 Y 2 Sheets-Sheet 2 INVENTOR.FRIEDRICH jCH ICHIFK A rromvsvs United States PatentO BALL POINT PENFriedrich Schachter, 7333 W. Harrison St., Forest Park, Ill.

Filed Sept. 8, 1958, Ser. No. 759,827 '7 Claims. (Cl. 29-1484) Thisinvention relates to a writing point construction for ball point pensand to the art of fabricating the same, and has as its general object toprovide an improved, long wearing, better-writing point, particularlyadapted for writing on surfaces (such as glossy surfaces) which normallycause a 'ball point pen to skip.

One of the objects of my invention is to provide a writing point thatwill write on all surfaces without embodying the disadvantages of thosepoints which are particularly designed for writing on glossy surfaces.

My investigation of this type of pen in which a special effort has beenmade to attain continuous writing on smoothsurfaces (and other surfacestending to cause skipping, such as surfaces having finger prints orother coatings that tend to lubricate the surface or to otherwisedestroy or reduce the traction between the ball and the surface)indicates that such pens (which usually utilize a ball with a pittedsurface for increased traction) customarily have the followingdisadvantages:

(a) Increase of ink consumption over the life of the writing unitcartridge;

(b) A gradual change (thickening) in the intensity of the line due towear and the loading of the pitted'surface with an accumulation of aforeign matter picked up from the writing surface and mixed with theink, and which eventually tends to starve the ink flow;

(c) A rough feeling (of dragging resistance) transmitted to the fingersof the writer in the writing operation;

(d) The build-up of excessive ink (development of blobs) on the exposedareas of the point assembly;

(e) Slow starting, i.e., failure to produce a line at the beginning of apen stroke, when the pen is first picked up for use after a short periodof non-use;

(f) Splitting of lines during directional change in writing caused byinsufficient ink feed at a change of direction of the writing path or bylateral shifting of the ball in its socket.

A principal object of the present invention is to provide a ball pointpen especially adapted for continuous writing on all types of surfacesand which in addition will overcome the foregoing disadvantages.

More specifically, the invention contemplates such a pen which willprovide consistent writing performance over long periods ofuse;'will.avoid change in line intensity; will maintain uniform inkconsumption; will not form or deposit blobs on the writing surface; willexclude the entry of foreign particles into the ball socket; will avoidclogging arising from the picking up of foreign material from thewriting surface; will produce a line of color intensityeven when movedover the'writing surface without any writing pressure applied theretoother than the mere weight of the pen itself; will provide smoothrolling of the ball without any feelingof drag against the paper; andwill avoidthe splitting of lines.

Ingeneral, the inventionsolves the problems presented above by reducinginternal friction in the point. A primary aspect of the invention inthis'connection is to pro vide a ball seat which (a) has an extremelysmooth surface, within the range referred to in present day industrialmechanicsas a super-finish and (b) a seat having true geometricalconformity to the contour of the writing ball. On this aspect of thesituation, I have observed that in the average ball point assembly(which under common present day practice is formed by impressing theball into the seat) the seat does not accurately conform to the ballsurface, due to spring-back which occurs in the metal of the seatsubsequent to the seat forming operation. My experiments have shown thatthe seat which constitutes the bottom of the ball socket should be wearresistant, highly malleable material, while the lip which constitutesthe side walls of the socket should be of a material 7 suitable tofirmly position and retain the ball, minimizing the tendency to yieldwhile the seat is being formed, and to provide socket walls resistingexpansion under writing pressure.

I am aware that many prior workers and patentees in this art havediscussed at length the problem of wear of the ball against its .seatand have proposed many remedies, but so far as I am aware none of themhave discovered the particular combination of features by which theproblem is solved in the present invention.

The invention further contemplates a method of fabricating an insertseat and a method to achieve control of the geometrical condition of theball socket.

Other objects and advantages will become apparent in the ensuingspecification .and appended drawing in which:

Fig-1 is an axial sectional view, on a magnified scale, of the tip of aball point pen embodying my invention;

Fig. 2 is a similarly magnified fragmentary axial sectional view,showing astage in the assembly of parts constituting said tip;

Fig. 3 is .a transverse sectional view of the tip taken onthe line 3-3of Fig. 1; I

Fig. 4 is a fragmentary axial sectional view of a pen tip embodying amodified form of the invention;

Figs. 5-7 illustrate processing steps.

Referring now to the drawings in detail, I have shown in Figs. 1 and 3thereof,as an example of a preferred form of the invention, a writingpoint assembly embodying, in general, a barrel tip, generally referredto by the character A; a writing ball B retained in the tip A, and aseat C providing a thrust bearing for the ball B as it rotates during awriting operation.

The socket A includes a base portion 16} having an ink passage bore 11and having an external wall 12 which may either be cylindrical or frustoconical or double curved, as selected. Extending beyond the base portion'10 is a lip 13 of circular cross section having an internal wall 14(which may be cylindrical) and having an offset annular supportingshoulder 15 extending from the bore 11 to the internal wall 14. Wall 14and shoulder 15 cooperatively define an ink well in which ink flowingthrough the base passage 11 may spread aroundthe ball B preliminaryto-being carried by the ball to the writing surface. The shoulder 15 maybe frusto conicalas shown, or of any other suitable contour forsupporting the seat C.

Beyond the cylindrical wall 14, the' lip 13 has an internal bearing wall16 formed as an equatorial zone of 'a sphere, and conformed closely tothe surface of the in the forming .of the ball seating surface in theseat C i I I (by, pressing the ball B againstthe seat) there will be .nodeformation in the lip13 arising from expansion-of.

, seat ,O. under the coining pressure ofthe seat forming ?atented Jan.31, 1961 Y device (either the ball B or a special tool with ahemispherical end corresponding to the surface of the ball).

In this particular form of the invention, the seat C is of modifiedtorus form, and this form is attained by the deformation of a ring ofcircular cross sectional wire as will presently be described. The seatcomprises a cir- 'cumferentially continuous outer body portion 18 havingrespective outer annular surfaces conformed generally by the formingpressure) to the shoulder and to the internal wall 14 and an innerportion having a plurality of circumferentially spaced bearing surfaces19 consisting in zonal segments of a spherical surface conformed to thesurface of the ball B and interrupted by a corresponding series ofintervening ink passages 20. Although a generally triangular notch formis disclosed, the passages 20 may be of any selected cross section.Also, as shown in Fig. 4, the passages Zita may be disposed on the outerside of seat C, between the same and the internal wall surface 14 andshoulder 15, and the seating face 19.

The ink passage notches may be aligned with the socket axis (comically,as shown in Fig. 1). Alternatively, the passages may be disposeddiagonally with respect to respective radii, i.e., tangential to acircumference at or within the radius of ink supply bore 11.

The ball B preferably has a smooth, highly finished surface, althoughthe invention contemplates the possibility of using a ball with a smoothspherical surface pitted by a large number of minute cavities. Thematerial of the ball, as previously indicated, is so related to that ofthe seat as to provide a readily dissipating characteristic in any alloythat may be formed by welding of molecules of the ball to those of theseat (in the case where both ball and seat are of metal). For example,the ball may be of tungsten carbide with a surface finish of 1 microinch (R.M.S.) smoothness.

The seat C is of a wear resistant material which, although tough, isextremely soft, i.e. highly malleable, so as to faithfully mirror thecoining surface of the ball (or a coining tool) used in shaping thebearing surfaces of the seat. A low coefficient of friction ispreferred.

The seat may be a silver alloy such as coin silver (approximately 10%copper and 90% silver) or platinum iridium (approximately 90% platinumand 10% iridium) or tellurium copper /z% tellurium and 99 /2% copper,approximately). Each of these alloys has the characteristic of softnesshereinbefore described. As another example of a suitable material, theseat may be an alloy of one of the platinum group metals and the selflubricating substance such as molybdenum disulfide, added thereto insuflicient quantity to provide the low coefiicient of friction. Anothermaterial (not wholly metallic) that can be used is a sintered mixture ofTeflon (tetrafluoroethylene resin) particles and particles of a suitablemetal, or any of the resins in the fluoro-carbon group closely allied toTeflon, such as Kel-F resin; or any equivalent plastic material.

Alternatively, the ball may be of a material such as sapphire orhardened glass or other ceramic substance such as sintered aluminumoxide or sintered glass, or other suitably hard material.

The lip 13 is of considerably harder material than the seat C. Forexample, the lip (and in fact the entire socket unit A) can befabricated from free-machining brass or bronze in accordance withconventional practice in this art.

Method of fabricating Referring first to the preferred form of theinvention shown in Fig. 1, the method of fabricating this point assemblyis shown in part in the related Fig. 2, which illustrates the parts inan intermediate stage of fabrication. The lip 13 will be seen to have asubstantially uniform flare out to its end, which has a greater wallthickness than that of the finished tip as shown in Fig. 1. The internalcylindrical wall 14x extends uniformly to the tip. 'Its diameter is suchas to barely receive the ball B. The seat Cx is of true toroidal form,and is fabricated from a short length of fine soft wire of one of thesoft materials previously indicated, the ends of the length of wirebeing carefully formed so as to provide, in effect, a closed ring wheninserted in the socket. Because of the extreme smallness of the ring,the invention contemplates, as a preferred method, the forming of thering on an attachment of the ball assembly machine either bystraightening and cutting off the proper length from straight wire,forming it around a mandrel, preferably using the mandrel to feed thering into the socket; or by forming a continuous helical coil from whichone turn at a time is severed and fed into the socket to form the seatring. Alternatively, a true ring can be formed on the end of thetangential stretch of wire, cut off at the 360 point and moved along itsaxis into the socket, or straight lengths of wire may be cut to theproper length and then formed into rings.

The seat forming operation may include the element of softening the seatby heating the same immediately prior to or simultaneous with theimpressing of the ball surface therein.

In fabricating the socket A, I start with a solid block of suitablemetal, and shape the exterior thereof. Simultaneously therewith, orthereafter, the internal machining is performed to provide the inksupply bore 11 and the internal wall 14 of the lip 13, as well as theshoulder 15. The seat C is then inserted into the socket (the inkpassages formed previously or subsequently) and the ball B is insertedover the seat, to provide the assembly shown in Fig. 2.

In the next step of the process, pressure is applied to the ball througha suitable tool (not shown) to press the ball firmly against the annularring of wire constituting the seat C in its initial form. Alternatively,a tool with an integral semi-spherical end, may be employed in lieu ofusing the ball B. The pressure causes the seat ring C to be deformed tothe shape illustrated in Fig. l, the bearing surfaces 19. Because of thehigh ductility of the metal in the seat ring C, there is no appreciablespring-back when the pressure is released.

Either simultaneously with this operation of forming the bearingsurfaces in the seat, or either before or after the seating operation,the lip 13 is drawn inwardly to form an equatorial zone encircling theball.

An important aspect of the invention, in solving the above mentionedproblems, is that of providing improved concentricity between theinternal and external walls of the socket, thereby providing improveduniformity in the wall structure and its yielding to the formingactionin which the socket is formed around the ball.

Figs. 5 and 6 illustrate a seat-forming operation in which a straightlength of soft wire 30 is fed as indicated by the arrow thereon into agap between a movable female die 31 to a point where it is arrestedagainst a stop 32 which constitutes one of a pair of guides 32 and 33 inwhich the die 31 is slidably mounted. Then the die 31 is advancedtransversely of wire 30 as indicated by its arrow, shearing a shortlength 30' from the end of wire 30 as indicated at 34 and wrapping thisshort length 36' around a fixed mandrel 36 projecting at right angles tothe plane of die 31 to form the seat ring C, the wrapping movement beingcompleted by a pair of curling jaws 37 moving together on a line tangentto the periphery of the formed seat ring C along the path indicated bytheir respective arrows. The ring C is then ejected from the mandrel 36in a direction parallel to the axis thereof by an ejection sleeve 38seen in Figs. 5 and 9. A socket A, presented to the mandrel 36 incoaxial relation thereto, receives the completed ring C as an insert, asshown in Fig. 7, and continued movement of sleeve 38 may be utilized tomove the assembly of ring C and socket A ofi the mandrel 36 (and ifdesired at the same time the end of sleeve 38 may impress the inkpassages 20 into the ring C).

I claim:

1. A method of fabricating a thrust bearing for a writing ball comprisedof a socket, said socket having a ball receiving bore, an annularshoulder projecting inwardly from the base of said bore, an annular lipsurrounding and defining said bore, and means for conducting ink from areservoir to said bore, and an inserted ring having a face permanentlyconforming to the contour of the ball, which ring is of uniform crosssection and is deformable without appreciable spring back, said methodincluding the following steps: fashioning said socket of suflicient bulkand from material of suflicient strength to retain its originaldimensions when the socket is supporting said ring in an operation offorming the ring; fashioning from a length of malleable wire of materialhaving no appreciable spring back, a split ring, said wire being softerthan the material of the socket and the ball, said length of wire beingsuch as to provide a substantially closed ring having a diametercorresponding to said bore; inserting the ring into the bore; applying asubstantially unyielding spherical surface against the face of the ringto deform the ring to form a thrust bearing surface concentric with saidbore having true geometric conformity equivalent to the contour of thewriting ball and simultaneously forcing the ring to conformcircumferentially to the walls and shoulder at the base of said bore,but the deforming being limited to an amount that no appreciable springback is developed due to the forming operation, the annular shoulderbeing of such size as to support and hold the ring in position and tooppose the forces applied to the face of the ring both during and afterthe deformation.

2. The method as set forth in claim 1, wherein the deforming pressureapplied against the ring is limited so as to provide an annular ink wellof substantial extent in said socket between the exposed contour of thebearing ring and the intersection of the ball and the socket wall.

' 3. A method as set forth in claim 1 wherein the surface of the ballseat has a smooth finish within the range referred to in present dayindustrial mechanics as a super finish.

4. The method defined in claim 1, wherein said wire has circular crosssection.

5. The method defined in claim 1, wherein the wire is fed in acontinuous length to an apparatus cutting off an exact length, forming aring and injecting the same into the bore of said socket.

6. The method defined in claim 1, including the additional step ofproviding said ring with a plurality of ink channels to assure a uniformflow of ink from said reservoir to said writing ball.

7. The method defined in claim 1, wherein the wire ends are cut atangles providing substantially parallel faces when the ring is closed.

References Cited in the file of this patent UNITED STATES PATENTS2,267,229 Zimmerman et al Dec. 23, 1941 2,718,051 Cloutier Sept. 20,1955 2,834,321 Dufresne May 13, 1958 2,847,975 Lawton Aug. 19, 19582,855,665 Alldredge Oct. 14, 1958 FOREIGN PATENTS 945,809 France Dec. 6,1948 1,108,400 France Aug. 31, 1955 935,473 France Jan. 16, 1956(Addition to No. 66,051)

